Probability Seminar

Marcus MichelenUniversity of Illinois Chicago
New lower bounds for sphere packings and independence sets via randomness

Monday, February 12, 2024 - 4:00pm
Malott 406

We show new lower bounds for sphere packings in high dimensions and for independent sets in graphs with not too large co-degrees. For dimension d, this achieves a sphere packing of density (1 + o(1)) d log d / 2^(d+1). In general dimension, this provides the first asymptotically growing improvement for sphere packing lower bounds since Roger's bound of c*d/2^d in 1947. The proof amounts to a random (very dense) discretization together with a new theorem on constructing independent sets on graphs with not too large co-degree. Both steps will be discussed, and no knowledge of sphere packings will be assumed or required. This is based on joint work with Marcelo Campos, Matthew Jenssen and Julian Sahasrabudhe.